Speed up JUnit tests by running them in parallel

By running multiple JUnit tests at the same time you can cut down on overall test time.

Dependencies

Add the following dependencies to your project. The example below uses commons-io for saving screenshots to disk:

Maven (pom.xml):

<dependency>
    <groupId>org.seleniumhq.selenium</groupId>
    <artifactId>selenium-java</artifactId>
    <version>4.33.0</version>
</dependency>
<dependency>
    <groupId>junit</groupId>
    <artifactId>junit</artifactId>
    <version>4.13.2</version>
    <scope>test</scope>
</dependency>
<dependency>
    <groupId>commons-io</groupId>
    <artifactId>commons-io</artifactId>
    <version>2.16.1</version>
</dependency>

Gradle (build.gradle):

implementation 'org.seleniumhq.selenium:selenium-java:4.33.0'
testImplementation 'junit:junit:4.13.2'
implementation 'commons-io:commons-io:2.16.1'

Helper class needed to run JUnit tests in parallel

import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;

import org.junit.runners.Parameterized;
import org.junit.runners.model.RunnerScheduler;

public class Parallelized extends Parameterized {

    private static class ThreadPoolScheduler implements RunnerScheduler {
        private ExecutorService executor;

        public ThreadPoolScheduler() {
            String threads = System.getProperty("junit.parallel.threads", "16");
            int numThreads = Integer.parseInt(threads);
            executor = Executors.newFixedThreadPool(numThreads);
        }

        @Override
        public void finished() {
            executor.shutdown();
            try {
                executor.awaitTermination(10, TimeUnit.MINUTES);
            } catch (InterruptedException exc) {
                throw new RuntimeException(exc);
            }
        }

        @Override
        public void schedule(Runnable childStatement) {
            executor.submit(childStatement);
        }
    }

    public Parallelized(Class<?> klass) throws Throwable {
        super(klass);
        setScheduler(new ThreadPoolScheduler());
    }
}

Below is a JUnit Test example, which uses the above helper class to run the test in parallel.

import java.io.File;
import java.io.IOException;
import java.net.URI;
import java.util.HashMap;
import java.util.LinkedList;
import java.util.Map;

import org.apache.commons.io.FileUtils;
import org.junit.After;
import org.junit.Before;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.junit.runners.Parameterized;
import org.openqa.selenium.MutableCapabilities;
import org.openqa.selenium.OutputType;
import org.openqa.selenium.TakesScreenshot;
import org.openqa.selenium.WebDriver;
import org.openqa.selenium.remote.RemoteWebDriver;

@RunWith(Parallelized.class)
public class JUnitParallel {
    private String platform;
    private String browserName;
    private String browserVersion;

    @Parameterized.Parameters
    public static LinkedList<String[]> getEnvironments() throws Exception {
        LinkedList<String[]> env = new LinkedList<>();
        env.add(new String[]{"WIN11", "chrome", "latest"});
        env.add(new String[]{"WIN11", "firefox", "latest"});
        env.add(new String[]{"WIN11", "MicrosoftEdge", "latest"});

        // Add more browser configurations here

        return env;
    }

    public JUnitParallel(String platform, String browserName, String browserVersion) {
        this.platform = platform;
        this.browserName = browserName;
        this.browserVersion = browserVersion;
    }

    private WebDriver driver;

    @Before
    public void setUp() throws Exception {
        String key = System.getenv("TESTINGBOT_KEY");
        String secret = System.getenv("TESTINGBOT_SECRET");
        String hubURL = "https://" + key + ":" + secret + "@hub.testingbot.com/wd/hub";

        MutableCapabilities options = new MutableCapabilities();
        options.setCapability("browserName", browserName);
        options.setCapability("browserVersion", browserVersion);
        options.setCapability("platformName", platform);

        Map<String, Object> tbOptions = new HashMap<>();
        tbOptions.put("name", "Parallel JUnit Test");
        tbOptions.put("build", "build-1");
        options.setCapability("tb:options", tbOptions);

        driver = new RemoteWebDriver(URI.create(hubURL).toURL(), options);
    }

    @Test
    public void testSimple() throws Exception {
        driver.get("https://www.google.com");
        String title = driver.getTitle();
        System.out.println("Page title is: " + title);

        File srcFile = ((TakesScreenshot) driver).getScreenshotAs(OutputType.FILE);
        try {
            FileUtils.copyFile(srcFile, new File("Screenshot.png"));
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    @After
    public void tearDown() throws Exception {
        driver.quit();
    }
}

Run the tests with mvn test. Note that the Maven Surefire plugin only picks up test classes whose names match *Test, Test*, *Tests or *TestCase by default. The example class above is named JUnitParallel, so either rename it (for example JUnitParallelTest) or add an explicit <includes> entry to the Surefire configuration, otherwise mvn test will run zero tests.

The number of parallel threads is controlled by the junit.parallel.threads system property (default 16 in the helper class above). Set this to match the number of parallel sessions allowed on your TestingBot plan to avoid queuing, for example mvn test -Djunit.parallel.threads=5.

Specify Browsers & Devices

To let TestingBot know on which browser/platform/device you want to run your test on, you need to specify the browsername, version, OS and other optional options in the capabilities field.

Testing Internal Websites

We've built TestingBot Tunnel, to provide you with a secure way to run tests against your staged/internal webapps.
Please see our TestingBot Tunnel documentation for more information about this easy to use tunneling solution.

The example below shows how to easily run a JUnit test with our Tunnel:

1. Download our tunnel and start the tunnel:

java -jar testingbot-tunnel.jar key secret

2. Adjust your test: instead of pointing to 'hub.testingbot.com/wd/hub' like the example above - change it to point to your tunnel's IP address.
Assuming you run the tunnel on the same machine you run your tests, change to 'localhost:4445/wd/hub'. localhost is the machine running the tunnel, 4445 is the default port of the tunnel.

This way your test will go securely through the tunnel to TestingBot and back:

@Before
public void setUp() throws Exception {
    MutableCapabilities options = new MutableCapabilities();
    options.setCapability("browserName", browserName);
    options.setCapability("browserVersion", browserVersion);
    options.setCapability("platformName", platform);

    Map<String, Object> tbOptions = new HashMap<>();
    tbOptions.put("name", "Parallel Tunnel Test");
    tbOptions.put("build", "build-1");
    options.setCapability("tb:options", tbOptions);

    driver = new RemoteWebDriver(URI.create("http://localhost:4445/wd/hub").toURL(), options);
}

Mark tests as passed/failed

To see if a test passed or not in our member area, or to send additional meta-data to TestingBot, you need to use our API.

TestingBot has a Java client for using the TestingBot API.

Maven:

<dependency>
    <groupId>com.testingbot</groupId>
    <artifactId>testingbotrest</artifactId>
    <version>1.0.10</version>
</dependency>

Gradle:

implementation 'com.testingbot:testingbotrest:1.0.10'

Once included with your tests, you can send back test status and other meta-data to TestingBot:

import com.testingbot.testingbotrest.TestingbotREST;
import org.junit.After;
import org.openqa.selenium.remote.RemoteWebDriver;
import java.util.HashMap;
import java.util.Map;

@After
public void tearDown() throws Exception {
    TestingbotREST api = new TestingbotREST(System.getenv("TESTINGBOT_KEY"), System.getenv("TESTINGBOT_SECRET"));
    Map<String, Object> data = new HashMap<>();
    data.put("success", "1");
    data.put("name", "My Test");
    api.updateTest(((RemoteWebDriver) driver).getSessionId().toString(), data);
    driver.quit();
}

Other Java Framework examples

JUnit
JUnit is a unit testing framework for the Java programming language.
Parallel JUnit
By running multiple JUnit tests at the same time you can cut down on overall test time.
TestNG
TestNG is a framework similar to JUnit and NUnit, which supports some additional commands and features.
TestNG + Cucumber
Run tests with TestNG and BDD Cucumber.